The influence of codoping on optical properties and glass connectivity of silica fiber preforms

Description

Rare Earth Elements-doped glasses have applications in many fields, and for example, Al and Ce codoping in silica optical fibers is usually done to attenuate the optical degradation (photodarkening) of, e.g. Yb and Tm doped silica optical fibers. To shed some light on the effect of codoping on the optical properties and the glass structure of SiO 2 fibers, we investigated a SiO 2 fiber preform having a gradual increase of the CeO 2 + Al 2 O 3 content from 1.5 to 6.3 mol% and a CeO 2 /Al 2 O 3 molar ratio varying from 0.04 to 1.4. Raman and photo-luminescence spectroscopies have been used to evaluate changes in the short-and medium-range order both in the cladding and in the core portions, and the evolution of the glass optical properties, respectively. The variations of the excitation and emission have been linked to modifications in the vibration bands of the Raman spectra, and in turn, the relationship between optical properties and glass connectivity has been carefully considered. Our results show that there is a strong positive linear relationship between the increase of the Raman bands in the high-frequency range and the red-shift of the excitation maxima. Therefore, the change of < Ce-O > distances and bond covalency character influences, in the same way, both the photoluminescence behavior of the core and the connectivity of the amorphous network.

Abstract

International audience

Additional details